US4018971A - Gels as battery separators for soluble electrode cells - Google Patents

Gels as battery separators for soluble electrode cells Download PDF

Info

Publication number
US4018971A
US4018971A US05/707,124 US70712476A US4018971A US 4018971 A US4018971 A US 4018971A US 70712476 A US70712476 A US 70712476A US 4018971 A US4018971 A US 4018971A
Authority
US
United States
Prior art keywords
membrane
gel
silicate
hydrochloric acid
powdered silica
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/707,124
Inventor
Dean W. Sheibley
Randall F. Gahn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Aeronautics and Space Administration NASA
Original Assignee
National Aeronautics and Space Administration NASA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Aeronautics and Space Administration NASA filed Critical National Aeronautics and Space Administration NASA
Priority to US05/707,124 priority Critical patent/US4018971A/en
Application granted granted Critical
Publication of US4018971A publication Critical patent/US4018971A/en
Priority to JP8517477A priority patent/JPS5313142A/en
Priority to AU27133/77A priority patent/AU508895B2/en
Priority to IT12695/77A priority patent/IT1081026B/en
Priority to CA283,070A priority patent/CA1080303A/en
Priority to DE2732481A priority patent/DE2732481C2/en
Priority to GB30274/77A priority patent/GB1580954A/en
Priority to FR7722292A priority patent/FR2358920A1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/18Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
    • H01M8/184Regeneration by electrochemical means
    • H01M8/188Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/449Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491Porosity
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/414Synthetic resins, e.g. thermoplastics or thermosetting resins
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/411Organic material
    • H01M50/414Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417Polyolefins
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409Separators, membranes or diaphragms characterised by the material
    • H01M50/449Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/50Fuel cells

Definitions

  • Redox cells having soluble electrodes in both the charged and discharged states, have been the object of increased interest as a method for the efficient storage of electrical energy. Such redox cells could store energy generated from time dependent energy sources such as solar electric and windmill electric installations.
  • Rechargable redox cells can be of the type which can be recharged by chemical or by electrical means.
  • a chemical recharging cell can operate with the overall reaction sequence being the combination of carbon with oxygen to yield carbon dioxide.
  • air would reoxidize ferrous ions to the ferric state or bromide ion to elemental bromine or the Br 3 - ion on the cathode side while hot activated carbon beds would reduce the ferric ions to the ferrous state.
  • An electrically rechargable redox flow cell can be more efficiently utilized in conjunction with an electric generating installation such as a solar or windmill electric station.
  • Electrically rechargable redox flow cells of the type in which the gels of the present invention are useful as separators are described in NASA Technical Memorandum TMX-71540 which is hereby incorporated by reference.
  • these redox flow cells contain two storage tanks, each containing one of the two metal ions which make up the redox couple. Although almost any redox couples can be used in such a cell, considerations regarding efficiency can be made in the choice of the particular couple.
  • the cathodic fluid e.g., aqueous concentrated Fe + 3
  • the anodic fluid e.g., aqueous concentrated Ti + 3
  • the power that can be withdrawn from or put back into the system depends on many factors including the tank volumes, the flow rates and the electrochemical features of the particular redox couple utilized and the characteristics of the electrode compartments.
  • the fluid In a two tank system employing multiple passes of the fluid, the fluid would constantly be recycled after passage through the fuel cell. In a four tank system, the fluids would pass from their respective tanks through the fuel cell and then into two other storage tanks. The system could then be electrically recharged by applying a suitable voltage to the terminals of the power conversion section section as the fluids are pumped back up to the original tanks.
  • the membrane utilized must provide an impermeable barrier to the cations of the particular couple utilized. However, the membranes must be permeable to the extent of maintaining the charge neutrality of each compartment by the migration of the anion used through the membrane. It should be noted that fuel cells can be designed with either anions or cations migrating through the membrane to provide the neutralization required. However, their is an inherent disadvantage from an energy standpoint in moving cations from the anode compartment during discharge as opposed to moving anions from the cathode compartment. That is, if a hydrogen cation is required to migrate during discharge, one mole of hydrochloric acid is required per Faraday over and above any acid that may be required for pH adjustment needed for solution stablilization.
  • Anions that can be used with the gels of the present invention include halide ions such as chloride and bromide.
  • anion-permeable membranes include polymers such as IONAC 3475. Such membranes can be made by grinding a quaternary ammonium ion-exchange resin to a powder and then polymerizing a monomer in the presence of the thus-formed powder. Additionally, a web can be used in conjunction with the membranes to provide support.
  • prior art structures include ceramic membranes such as those described in U.S. Pat. No. 3,392,103 issued to Carl Berger.
  • An object of the present invention is a medium that can be used in the construction of a membrane for use in bulk electrical energy storage systems having low ionic resistivity high selectivity for anions as opposed to metal cations and low electronic conductivity.
  • a further object is a membrane composition having a high mechanical strength, good wetting characteristics, no current density or voltage effects and no polarizability.
  • a further object of the present invention is to provide a membrane which results in increased power delivery from a given system.
  • a further object of the present invention is a membrane which operates by a simple mechanism and avoids the use of ion-exchange resins.
  • a further object of the present invention is a membrane which is physically compatable with the environment of a flow cell to the extent of allowing prolonged exposure to an oxidative acid environment.
  • a mineral-acid silica gel possesses the desirable characteristics of a low resistance and a high compatability with a fuel cell environment.
  • This gel can be present in the membrane in a variety of modes, the preferred constructions being a foam sheet impregnated with the gel and a porous polymer envelope into which the gel is placed with the subsequent sealing of all sides of the envelope.
  • FIG. 1 shows an electrically rechargeable bulk power storage system.
  • the anodic fluid and cathodic fluid tanks are represented by 1 and 2, respectively.
  • Pipelines for the feeding operation to the redox flow cell are labelled 3.
  • the redox flow cell 4 contains inert electrodes 5 and a selective membrane 6. After passing through the cell, the fluids are returned to tanks 1 and 2 by pumps labelled 7.
  • FIG. 2 represents a redox flow cell which can be used as 4 in FIG. 1.
  • An anodic fluid e.g., containing a Ti + 3 /TiO + 2 couple, primarily in its reduced state of Ti + 3 ions is fed through inlet 8 while cathodic fluid, e.g., containing a Fe + 2 /Fe + 3 couple, primarily in its oxidized state of Fe + 3 is fed through inlet 9.
  • the fluids then contact the inert electrodes 5 which may be an inert substance such as a graphitized fabric or felt.
  • the selective membrane 6 separates the compartments and permits passage of anions to maintain charge neutrality.
  • FIG. 3 represents a construction of a selective membrane 6 according to this invention.
  • An envelope 10, sealed on three sides, of a microporous polymeric sheet is filled in with the gel 11 of the present invention after which the last side can be closed by conventional means such as heat sealing with heating rollers 12.
  • FIG. 4 shows a second construction of a selective membrane according to this invention.
  • the gel 11 is placed between two sheets of polymeric material 13 and the composite is then pressed until the gel 11 is evidenced at the outer surfaces 14 of the sheets.
  • gels comprising a gelling agent such as silica and a mineral acid such as hydrochloric acid can provide an excellent medium for the selective transference of ions.
  • a gelling agent such as silica
  • a mineral acid such as hydrochloric acid
  • the gelling agents of this invention comprise inorganic materials such as silica and silicates including saponite, a magnesium lithium silicate, hectorite, a lithium aluminum silicate and magnesium zirconium silicate. These gelling agents can be used alone or in combination. However, the gelling agent composition as a whole should have an average particle diameter of less than about 0.1 microns. Therefore, the gelling agents of the present invention can be a wide range of silicas, talcs and clays.
  • silica and fumed silica are preferred.
  • a suitable fumed silicon dioxide is available from the Cabot Corporation under the name "Cab-O-Sil" which has a surface area of over about 100 square meters per gram.
  • silicates, talcs or clays have been used as the sole gelling agents in the gels of the present invention, it has been found that silica or silica in combination with these materials can provide preferred gels in view of their resulting in a lower resistance of the overall membrane.
  • the resistance of the overall membrane is preferable less than about 0.5 ohms.
  • the acids which can be used in the gels of the present invention are mineral acids, preferably hydrochloric acid since the chloride ion is a preferred anion for use with the cation couples in the redox systems which have been proposed and used.
  • the normality of a given volume of acid is inversely proportional to the amount of a given gelling agent needed to produce a gel. That is, as the normality of a given volume of acid increases, water is replaced by acid and, therefore, less gelling agent is needed to produce a gel. Thus, normalities of less than about 0.5 are disadvantageous in that increased amounts of the gelling agent are required which increases the resistance of the gel and thus the membrane as a whole.
  • the acids for use in the gels of th present invention have normalities between about 0.5 and about 12, preferably between about 6 and 12.
  • the gels of the present invention can easily be formed by simply adding the gelling agent in a sufficient amount to produce a gel of the desired consistency.
  • the amount of gelling agent that must be added to a given weight of hydrochloric acid depends on the particular gelling agent used and especially on the particle size or surface area of the agent. Since a 6 to 12 normal hydrochloric acid solution is preferred, it has been found that the gelling agent should be added in an amount of about 5 to 40% by weight of the acid, depending on the particular agent utilized.
  • the gel can be used as an exchange medium in a variety of structures. Basically, the gel must either be enclosed in a micorporous envelope or must be impregnated into a micorporous sheet.
  • An example of the envelope arrangement is shown in FIG. 3 wherein an envelope 10 is constructed from two sheets of a micorporous polymeric material. The envelope is sealed by any conventional means, e.g., heat sealing, on two or more sides and the gel 11 is then placed between the two sheets in a sandwich arrangement. Finally, the remaining open sides are then sealed by any conventional method which produces a tight seal. In FIG. 3, the last side is shown to be sealed by means of heated rollers 12. Suitable materials for the sheets to be fastened into envelopes include CELGARD 3400-a which is a microporous polypropylene film of a thickness of about 1 mil.
  • microporous sheet material used to contain the gel of the present invention should have a void volume of at least about 40%, CELGARD having a void volume of about 60%.
  • a second structure which can be used to contain the gel of the present invention can be produced by a process shown in FIG. 4.
  • the gel of the present invention 11 is placed between two sheets 13 of a microporous material and pressure is applied to the outside surfaces 14 of the sheets in order to force the gel through the body of the sheets.
  • the pressure is discontinued and the thus-formed structure can be used as a membrane within the scope of the present invention.
  • Suitable micorporous sheet material which can be used in this arrangement include polyvinyl chloride foams such as the AMERACE foams produced by the Amerace Company of Butler, N.J. Such materials have been found to have a void volume of about 70%.
  • a third structure for containing the gel of the present invention can be produced by simply spreading the gel on one or both sides of a microporous sheet and wiping off excess gel.
  • such arrangements are somewhat less satisfactory then the two structures mentioned above and shown FIGS. 3 and 4 since this method tends to result in an increase of the washing out of the gel from the structure during use in a flow cell.
  • gels of the present invention can be used with other microporous materials such as microporous ceramic sheets.
  • the thickness of the membrane structure containing the gel of the present invention basically depends on the amount of resistance the system can tolerate in a practical sense. That is, in a given system, i.e., a specified flow cell with a given couple in a specified concentration, a higher power output will be obtained as the resistance of the membrane decreases in value. Thus, in a practical sense, the selection of the composition of the sheet materials as well as their thicknesses is made with a view toward the resistance of the final membrane product in a given redox flow cell.
  • the power of an electrical system is defined by the multiplication of the voltage by the current. It has unexpectedly been found that when using membranes containing the gels according to the present invention, consistently higher power outputs are obtained from a given cell over the output of the same cell using a commercial anion exchange membrane such as IONAC 3475.
  • the most preferred gelling agent has been found to be silica, such as the fumed silica available under the name "Cab-O-Sil", while the most preferred mineral acid is hydrochloric acid.
  • silicates such as magnesium zirconium silicate, magnesium lithium silicate or lithium aluminum silicate can be added in amounts up to about 5% by weight of the acid.
  • the following Table indicates the amounts of "Cab-O-Sil" which should be added to a given weight of a hydrochloric acid solution to yield the gels of the present invention.
  • the silica when using the "Cab-O-Sil" fumed silica which has a surface area of over 100 square meters per gram and a particle size of about 0.01 to 0.03 microns, the silica should be used in an amount from about 5 to about 20% by weight of the hydrochloric acid having a normality between 12 and 0.5.
  • the membranes containing the gels of the present invention operate by a mechanism whereby chloride ions contained in a compartment undergoing reduction, e.g., Fe + 3 to Fe + 2 , enter the membrane and cause chloride ions contained in the membrane at the opposite side to be displaced into the other compartment which is experiencing an oxidation, e.g., Cr + 2 to Cr + 3 .
  • This mechanism indicates that the gel of the present invention could also be used in an application where the permeability of hydrogen cations is desired.
  • such a system usually requires one mole of an acid such as hydrochloric acid per Faraday over and above any acid that might be required for pH adjustment needed for solution stablization.
  • Ionac 3475 membrane was placed in the flow cell used in Example 1 using the same anodic and cathodic fluids of the same concentration.
  • the discharge characteristics of this cell were as follows:
  • the cell body as shown in FIG. 2 is fabricated from polycarbonate plastic sheet (3 inches ⁇ 3 inches ⁇ 1/2 inch).
  • Inert electrodes 5 of graphite sheet or graphite cloth (11/2 inches ⁇ 11/2 inches) are located in respective compartments of the cell in contact with the membrane 6.
  • One electrode becomes the cathode, while the other becomes the anode depending on which reactant solution flows through each half cell compartment.
  • Each electrode is sealed in the cell with a rubber gasket around its periphery.
  • the Fe is the cathode and Ti is the anode.
  • Typical salt concentrations are 1 molar with concentrations as high as 4 molar having been used.
  • Data presented in Table II are for 1 molar solutions at room temperature discharging through a one ohm load resistor, which is not shown in the figure, connected to the electrodes 5 by suitable leads.
  • the gel of the present invention can provide a membrane which can result in a significantly higher power output as compared with the prior art ion-exchange resin membranes.
  • a gel was formed by the procedure described in Example 1 with 90 grams of 6 Normal hydrochloric acid, 10 grams of "Cab-O-Sil” brand fumed silica and 5 grams of magnesium zirconium silicate.
  • a membrane was made with the gel and two sheets of the polyvinyl chloride foam as described in Example 1. This membrane performed satisfactorily and gave output characteristics similar to those in Table II with a cell as described in Example 1.
  • a gel within the scope of this invention was formed by mixing 67.3 grams of saponite with 109 grams of 6 Normal hydrochloric acid.
  • the output characteristics of a membrane formed from this gel in a manner similar to the procedure described in Example 1 were similar to the membrane formed in Example 1.
  • the gels of the present invention can provide an excellent medium for the selective transference of anions. These gels can be used in a variety of membrane structures which can be made by a considerable number of processes.

Abstract

Gels are formed from silica powders and hydrochloric acid. The gels can then be impregnated into a polymeric foam and the resultant sheet material can then be used in applications where the transport of chloride ions is desired. Specifically disclosed is the utilization of the sheet in electrically rechargable redox flow cells which find application in bulk power storage systems.

Description

ORIGIN OF THE INVENTION
This invention was made by an employee of the U.S. Government and may be manufactured or used by or for the Government without the payment of any royalities thereon or therefor.
BACKGROUND OF THE INVENTION
1. Field of the Invention
It has become increasingly important in recent years to develop means of storing bulk quantities of electrical power. Redox cells, having soluble electrodes in both the charged and discharged states, have been the object of increased interest as a method for the efficient storage of electrical energy. Such redox cells could store energy generated from time dependent energy sources such as solar electric and windmill electric installations.
2. Description of the Prior Art
Rechargable redox cells can be of the type which can be recharged by chemical or by electrical means. A chemical recharging cell can operate with the overall reaction sequence being the combination of carbon with oxygen to yield carbon dioxide. Thus, air would reoxidize ferrous ions to the ferric state or bromide ion to elemental bromine or the Br3 - ion on the cathode side while hot activated carbon beds would reduce the ferric ions to the ferrous state.
An electrically rechargable redox flow cell can be more efficiently utilized in conjunction with an electric generating installation such as a solar or windmill electric station. Electrically rechargable redox flow cells of the type in which the gels of the present invention are useful as separators are described in NASA Technical Memorandum TMX-71540 which is hereby incorporated by reference. In their simpliest embodiments, these redox flow cells contain two storage tanks, each containing one of the two metal ions which make up the redox couple. Although almost any redox couples can be used in such a cell, considerations regarding efficiency can be made in the choice of the particular couple. Thus, systems such as the Fe+ 2 /Fe+ 3 //Ti+ 3 /TiO+ 2 and the Fe+ 2 /Fe+ 3 //Cr+ 3 systems are preferred. Thus, the cathodic fluid, e.g., aqueous concentrated Fe+ 3, and the anodic fluid, e.g., aqueous concentrated Ti+ 3, are fed from their respective tanks through the redox flow cell wherein the system can either be charged from an external source or can be discharged to release the stored electrical energy. The power that can be withdrawn from or put back into the system depends on many factors including the tank volumes, the flow rates and the electrochemical features of the particular redox couple utilized and the characteristics of the electrode compartments.
In a two tank system employing multiple passes of the fluid, the fluid would constantly be recycled after passage through the fuel cell. In a four tank system, the fluids would pass from their respective tanks through the fuel cell and then into two other storage tanks. The system could then be electrically recharged by applying a suitable voltage to the terminals of the power conversion section section as the fluids are pumped back up to the original tanks.
The membrane utilized must provide an impermeable barrier to the cations of the particular couple utilized. However, the membranes must be permeable to the extent of maintaining the charge neutrality of each compartment by the migration of the anion used through the membrane. It should be noted that fuel cells can be designed with either anions or cations migrating through the membrane to provide the neutralization required. However, their is an inherent disadvantage from an energy standpoint in moving cations from the anode compartment during discharge as opposed to moving anions from the cathode compartment. That is, if a hydrogen cation is required to migrate during discharge, one mole of hydrochloric acid is required per Faraday over and above any acid that may be required for pH adjustment needed for solution stablilization.
Therefore, redox fuel cells that use anion migration through the membrane are somewhat preferred. Anions that can be used with the gels of the present invention include halide ions such as chloride and bromide.
Materials that have been used as anion-permeable membranes include polymers such as IONAC 3475. Such membranes can be made by grinding a quaternary ammonium ion-exchange resin to a powder and then polymerizing a monomer in the presence of the thus-formed powder. Additionally, a web can be used in conjunction with the membranes to provide support.
However, these organic membranes suffer from the significant disadvantages of limited temperature characteristics, limited resistance to prolonged exposure to oxidative acid environments and limited mechanical strength. Failure of the membrane to maintain the desired characteristics can result in increasingly high resistance values or leakage of one fluid into the compartment of the other.
Among the prior art membranes are those described in U.S. Pat. No. 3,497,389 issued to Carl Berger et al. These membranes utilize inorganic additives of controlled water vapor characteristics capable of retaining water and providing water vapor pressures above 100° C. The additives can be mixed with the ion conducting material, e.g., zirconium phosphate, granulated and pressed into discs which are then sintered.
Further, prior art structures include ceramic membranes such as those described in U.S. Pat. No. 3,392,103 issued to Carl Berger.
OBJECT OF THE INVENTION
An object of the present invention is a medium that can be used in the construction of a membrane for use in bulk electrical energy storage systems having low ionic resistivity high selectivity for anions as opposed to metal cations and low electronic conductivity.
A further object is a membrane composition having a high mechanical strength, good wetting characteristics, no current density or voltage effects and no polarizability.
A further object of the present invention is to provide a membrane which results in increased power delivery from a given system.
A further object of the present invention is a membrane which operates by a simple mechanism and avoids the use of ion-exchange resins.
A further object of the present invention is a membrane which is physically compatable with the environment of a flow cell to the extent of allowing prolonged exposure to an oxidative acid environment.
SUMMARY OF THE INVENTION
It has now been found that the use of a mineral-acid silica gel possesses the desirable characteristics of a low resistance and a high compatability with a fuel cell environment. This gel can be present in the membrane in a variety of modes, the preferred constructions being a foam sheet impregnated with the gel and a porous polymer envelope into which the gel is placed with the subsequent sealing of all sides of the envelope.
DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an electrically rechargeable bulk power storage system. The anodic fluid and cathodic fluid tanks are represented by 1 and 2, respectively. Pipelines for the feeding operation to the redox flow cell are labelled 3. The redox flow cell 4 contains inert electrodes 5 and a selective membrane 6. After passing through the cell, the fluids are returned to tanks 1 and 2 by pumps labelled 7.
FIG. 2 represents a redox flow cell which can be used as 4 in FIG. 1. An anodic fluid, e.g., containing a Ti+ 3 /TiO+ 2 couple, primarily in its reduced state of Ti+ 3 ions is fed through inlet 8 while cathodic fluid, e.g., containing a Fe+ 2 /Fe+ 3 couple, primarily in its oxidized state of Fe+ 3 is fed through inlet 9. The fluids then contact the inert electrodes 5 which may be an inert substance such as a graphitized fabric or felt. The selective membrane 6 separates the compartments and permits passage of anions to maintain charge neutrality.
FIG. 3 represents a construction of a selective membrane 6 according to this invention. An envelope 10, sealed on three sides, of a microporous polymeric sheet is filled in with the gel 11 of the present invention after which the last side can be closed by conventional means such as heat sealing with heating rollers 12.
FIG. 4 shows a second construction of a selective membrane according to this invention. The gel 11 is placed between two sheets of polymeric material 13 and the composite is then pressed until the gel 11 is evidenced at the outer surfaces 14 of the sheets.
DETAILED DESCRIPTION OF THE INVENTION
It has now been found that gels comprising a gelling agent such as silica and a mineral acid such as hydrochloric acid can provide an excellent medium for the selective transference of ions. Although the gels of this invention find primary utility in the selective transference of halide ions such as chloride anions, the gels can, nevertheless, be easily put to use as a medium for the selective transference of hydrogen cations.
The gelling agents of this invention comprise inorganic materials such as silica and silicates including saponite, a magnesium lithium silicate, hectorite, a lithium aluminum silicate and magnesium zirconium silicate. These gelling agents can be used alone or in combination. However, the gelling agent composition as a whole should have an average particle diameter of less than about 0.1 microns. Therefore, the gelling agents of the present invention can be a wide range of silicas, talcs and clays.
Among the gelling agents, the use of silica and fumed silica in particular is preferred. A suitable fumed silicon dioxide is available from the Cabot Corporation under the name "Cab-O-Sil" which has a surface area of over about 100 square meters per gram. Although various silicates, talcs or clays have been used as the sole gelling agents in the gels of the present invention, it has been found that silica or silica in combination with these materials can provide preferred gels in view of their resulting in a lower resistance of the overall membrane. The resistance of the overall membrane is preferable less than about 0.5 ohms.
The acids which can be used in the gels of the present invention are mineral acids, preferably hydrochloric acid since the chloride ion is a preferred anion for use with the cation couples in the redox systems which have been proposed and used. The normality of a given volume of acid is inversely proportional to the amount of a given gelling agent needed to produce a gel. That is, as the normality of a given volume of acid increases, water is replaced by acid and, therefore, less gelling agent is needed to produce a gel. Thus, normalities of less than about 0.5 are disadvantageous in that increased amounts of the gelling agent are required which increases the resistance of the gel and thus the membrane as a whole. Further, normalities of more than about 12 are disadvantageous in that acid of such normalities can be described as "fuming" acids which have an adverse effect on the fuel cell and are difficult to handle. Therefore, the acids for use in the gels of th present invention have normalities between about 0.5 and about 12, preferably between about 6 and 12.
The gels of the present invention can easily be formed by simply adding the gelling agent in a sufficient amount to produce a gel of the desired consistency. The amount of gelling agent that must be added to a given weight of hydrochloric acid depends on the particular gelling agent used and especially on the particle size or surface area of the agent. Since a 6 to 12 normal hydrochloric acid solution is preferred, it has been found that the gelling agent should be added in an amount of about 5 to 40% by weight of the acid, depending on the particular agent utilized.
The gel can be used as an exchange medium in a variety of structures. Basically, the gel must either be enclosed in a micorporous envelope or must be impregnated into a micorporous sheet. An example of the envelope arrangement is shown in FIG. 3 wherein an envelope 10 is constructed from two sheets of a micorporous polymeric material. The envelope is sealed by any conventional means, e.g., heat sealing, on two or more sides and the gel 11 is then placed between the two sheets in a sandwich arrangement. Finally, the remaining open sides are then sealed by any conventional method which produces a tight seal. In FIG. 3, the last side is shown to be sealed by means of heated rollers 12. Suitable materials for the sheets to be fastened into envelopes include CELGARD 3400-a which is a microporous polypropylene film of a thickness of about 1 mil.
The microporous sheet material used to contain the gel of the present invention should have a void volume of at least about 40%, CELGARD having a void volume of about 60%.
A second structure which can be used to contain the gel of the present invention can be produced by a process shown in FIG. 4. In this arrangement, the gel of the present invention 11 is placed between two sheets 13 of a microporous material and pressure is applied to the outside surfaces 14 of the sheets in order to force the gel through the body of the sheets. When the gel is evident at the surfaces 14 of the sheet materials, the pressure is discontinued and the thus-formed structure can be used as a membrane within the scope of the present invention. Suitable micorporous sheet material which can be used in this arrangement include polyvinyl chloride foams such as the AMERACE foams produced by the Amerace Company of Butler, N.J. Such materials have been found to have a void volume of about 70%.
A third structure for containing the gel of the present invention can be produced by simply spreading the gel on one or both sides of a microporous sheet and wiping off excess gel. However, such arrangements are somewhat less satisfactory then the two structures mentioned above and shown FIGS. 3 and 4 since this method tends to result in an increase of the washing out of the gel from the structure during use in a flow cell.
It can be seen that the gels of the present invention can be used with other microporous materials such as microporous ceramic sheets.
The thickness of the membrane structure containing the gel of the present invention basically depends on the amount of resistance the system can tolerate in a practical sense. That is, in a given system, i.e., a specified flow cell with a given couple in a specified concentration, a higher power output will be obtained as the resistance of the membrane decreases in value. Thus, in a practical sense, the selection of the composition of the sheet materials as well as their thicknesses is made with a view toward the resistance of the final membrane product in a given redox flow cell.
The power of an electrical system is defined by the multiplication of the voltage by the current. It has unexpectedly been found that when using membranes containing the gels according to the present invention, consistently higher power outputs are obtained from a given cell over the output of the same cell using a commercial anion exchange membrane such as IONAC 3475.
The most preferred gelling agent has been found to be silica, such as the fumed silica available under the name "Cab-O-Sil", while the most preferred mineral acid is hydrochloric acid. Additonally, silicates such as magnesium zirconium silicate, magnesium lithium silicate or lithium aluminum silicate can be added in amounts up to about 5% by weight of the acid. The following Table indicates the amounts of "Cab-O-Sil" which should be added to a given weight of a hydrochloric acid solution to yield the gels of the present invention.
              TABLE I                                                     
______________________________________                                    
0.5 Normal HCl                                                            
              15 - 20% by weight of silica                                
6.0 Normal HCl                                                            
              8 - 10% by weight of silica                                 
12 Normal HCl 5 -  7% by weight of silica.                                
______________________________________                                    
As can be seen above, when using the "Cab-O-Sil" fumed silica which has a surface area of over 100 square meters per gram and a particle size of about 0.01 to 0.03 microns, the silica should be used in an amount from about 5 to about 20% by weight of the hydrochloric acid having a normality between 12 and 0.5.
While not wanting to be bound by theory, it is believed that the membranes containing the gels of the present invention operate by a mechanism whereby chloride ions contained in a compartment undergoing reduction, e.g., Fe+ 3 to Fe+ 2, enter the membrane and cause chloride ions contained in the membrane at the opposite side to be displaced into the other compartment which is experiencing an oxidation, e.g., Cr+ 2 to Cr+ 3. This mechanism indicates that the gel of the present invention could also be used in an application where the permeability of hydrogen cations is desired. However, as indicated above, such a system usually requires one mole of an acid such as hydrochloric acid per Faraday over and above any acid that might be required for pH adjustment needed for solution stablization.
The following non-limiting examples illustrate the use of the gels of the present invention.
EXAMPLE 1
10 grams of "Cab-O-Sil" brand fumed silica were added to 90 grams of a 6 Normal hydrochloric acid solution with mixing. After gellation occured, the gel was spread upon a sheet of Amerace brand microporous polyvinyl chloride foam having a thickness of about 20 mils. A second sheet of the polyvinyl chloride foam was then placed upon the first sheet and the laminate was pressed until the gel was evident at the surface of the polyvinyl chloride foam sheets. This structure had a total thickness of about 40 to 45 mils. and was used in a standard redox flow cell, the following output values being obtained.
              TABLE II                                                    
______________________________________                                    
Time (in minutes)                                                         
            Voltage  Current (in amperes)                                 
______________________________________                                    
0           .475     .4                                                   
20          .435     .365                                                 
35          .41      .35                                                  
52.5        .38      .33                                                  
77.5        .345     .30                                                  
147.5       .23      .19                                                  
177.5       .175     .15                                                  
200         .12      .125                                                 
247.5       .06      .06                                                  
______________________________________                                    
COMPARATIVE EXAMPLE 1
A commercially available Ionac 3475 membrane was placed in the flow cell used in Example 1 using the same anodic and cathodic fluids of the same concentration. The discharge characteristics of this cell were as follows:
              TABLE III                                                   
______________________________________                                    
Time (in minutes)                                                         
            Voltage  Current (in amperes)                                 
______________________________________                                    
0           .37      .315                                                 
10          .35      .30                                                  
20          .34      .29                                                  
30          .33      .28                                                  
40          .315     .27                                                  
70          .16      .15                                                  
75          .08      .075                                                 
80          .045     .04                                                  
______________________________________                                    
The cell body as shown in FIG. 2 is fabricated from polycarbonate plastic sheet (3 inches × 3 inches × 1/2 inch). Inert electrodes 5 of graphite sheet or graphite cloth (11/2 inches × 11/2 inches) are located in respective compartments of the cell in contact with the membrane 6. One electrode becomes the cathode, while the other becomes the anode depending on which reactant solution flows through each half cell compartment. Each electrode is sealed in the cell with a rubber gasket around its periphery.
Using the Fe+ 3 /Fe+ 2 and Ti+ 3 /TiO+ 2 couples, the Fe is the cathode and Ti is the anode. Typical salt concentrations are 1 molar with concentrations as high as 4 molar having been used. Data presented in Table II are for 1 molar solutions at room temperature discharging through a one ohm load resistor, which is not shown in the figure, connected to the electrodes 5 by suitable leads.
As can be seen above, the gel of the present invention can provide a membrane which can result in a significantly higher power output as compared with the prior art ion-exchange resin membranes.
EXAMPLE 2
A gel was formed by the procedure described in Example 1 with 90 grams of 6 Normal hydrochloric acid, 10 grams of "Cab-O-Sil" brand fumed silica and 5 grams of magnesium zirconium silicate. A membrane was made with the gel and two sheets of the polyvinyl chloride foam as described in Example 1. This membrane performed satisfactorily and gave output characteristics similar to those in Table II with a cell as described in Example 1.
EXAMPLE 3
A gel within the scope of this invention was formed by mixing 67.3 grams of saponite with 109 grams of 6 Normal hydrochloric acid. The output characteristics of a membrane formed from this gel in a manner similar to the procedure described in Example 1 were similar to the membrane formed in Example 1.
It can be seen that the gels of the present invention can provide an excellent medium for the selective transference of anions. These gels can be used in a variety of membrane structures which can be made by a considerable number of processes.
Therefore, it will be understood that various modifications and adaptions of the invention can be made by those skilled in the art without departing from the spirit of the invention and, accordingly, the invention is not taken as limited except by the scope of the following claims.

Claims (27)

We claim:
1. An ion transport medium comprising a gel of hydrochloric acid and powdered silica.
2. The ion transport medium of claim 1, wherein said hydrochloric acid is from about 0.5 to about 12 Normal.
3. The ion transport medium of claim 1, wherein said powdered silica is present in an amount of from about 5 to about 20% by weight of said hydrochloric acid.
4. The ion transport medium of claim 1, wherein said gel further comprises a silicate.
5. The ion transport medium of claim 4, wherein said silicate is selected from the group consisting of magnesium lithium silicate, lithium aluminum silicate and magnesium zirconium silicate.
6. The ion transport medium of claim 1, wherein said powdered silica has a surface area of about 100 square meters per gram.
7. The ion transport medium of claim 1, wherein said powdered silica has an average particle size of less than about 0.1 micron.
8. An ionic transport membrane comprising a microporous substrate which contains an ion transport medium comprising a gel of hydrochloric acid and powdered silica.
9. The ionic transport membrane of claim 8, wherein said hydrochloric acid is from about 0.5 to about 12 Normal.
10. The ionic transport membrane of claim 8, wherein said powdered silica is present in an amount from about 5 to about 20% by weight of said hydrochloric acid.
11. The ionic transport membrane of claim 8, wherein said gel further comprises a slicate.
12. The ionic transport membrane of claim 11, wherein said silicate is selected from the group consisting of magnesium lithium silicate, lithium aluminum silicate and magnesium zirconium silicate.
13. The ionic transport membrane of claim 8, wherein said powdered silica has a surface area of about 100 square meters per gram.
14. The ionic transport membrane of claim 8, wherein said powdered silica has an average particle size of less than about 0.1 micron.
15. The ionic transport membrane of claim 8, wherein said microporous substrate has a void volume of over about 40% without said gel.
16. The ionic transport membrane of claim 8, wherein said microporous substrate is an organic polymer.
17. The ionic transport membrane of claim 8, wherein said membrane has a resistance of less than about 0.5 ohms.
18. An electrical storage device comprising an anode, an anodic fluid, a cathode, a cathodic fluid and between said anodic and cathodic fluid, an inoic transport membrane comprising a microporous substrate which contains an ion transport medium comprising a gel of hydrochloric acid and powdered silica.
19. The electrical storage device of claim 18, wherein said hydrochloric acid is from about 0.5 to about 12 Normal.
20. The electrical storage device of claim 18, wherein said powdered silica is present in an amount of from about 5 to about 20% by weight of said hydrochloric acid.
21. The electrical storage device of claim 18, wherein said gel further comprises a silicate.
22. The electrical storage device of claim 21, wherein said silicate is selected from the group consisting of magnesium lithium silicate, lithium aluminum silicate and magnesium zirconium silicate.
23. The electrical storage device of claim 18, wherein said powdered silica has a surface area of about 100 square meters per gram.
24. The electrical storage device of claim 18, wherein said powdered silica has an average particle size of less than about 0.1 micron.
25. The electrical storage device of claim 18, wherein said microporous substrate has a void volume of over about 40% without said gel.
26. The electrical storage device of claim 18, wherein said microporous substrate is an organic polymer.
27. The electrical storage device of claim 18, wherein said membrane has a resistance of less than about 0.5 ohms.
US05/707,124 1976-07-20 1976-07-20 Gels as battery separators for soluble electrode cells Expired - Lifetime US4018971A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US05/707,124 US4018971A (en) 1976-07-20 1976-07-20 Gels as battery separators for soluble electrode cells
JP8517477A JPS5313142A (en) 1976-07-20 1977-07-18 Ion transfer medium for soluble electrode cell
GB30274/77A GB1580954A (en) 1976-07-20 1977-07-19 Electric storage devices
IT12695/77A IT1081026B (en) 1976-07-20 1977-07-19 BATTERY SEPARATORS FOR SOLUBLE ELECTRODE CELLS
AU27133/77A AU508895B2 (en) 1976-07-20 1977-07-19 Ion transport gel
CA283,070A CA1080303A (en) 1976-07-20 1977-07-19 Gels as battery separators for soluble electrode cells
DE2732481A DE2732481C2 (en) 1976-07-20 1977-07-19 Ion transfer means for use in a storage of electrical energy
FR7722292A FR2358920A1 (en) 1976-07-20 1977-07-20 IONIC CONDUCTION MEMBRANE GEL

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/707,124 US4018971A (en) 1976-07-20 1976-07-20 Gels as battery separators for soluble electrode cells

Publications (1)

Publication Number Publication Date
US4018971A true US4018971A (en) 1977-04-19

Family

ID=24840447

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/707,124 Expired - Lifetime US4018971A (en) 1976-07-20 1976-07-20 Gels as battery separators for soluble electrode cells

Country Status (8)

Country Link
US (1) US4018971A (en)
JP (1) JPS5313142A (en)
AU (1) AU508895B2 (en)
CA (1) CA1080303A (en)
DE (1) DE2732481C2 (en)
FR (1) FR2358920A1 (en)
GB (1) GB1580954A (en)
IT (1) IT1081026B (en)

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4370392A (en) * 1981-06-08 1983-01-25 The University Of Akron Chrome-halogen energy storage device and system
US4414090A (en) * 1981-10-01 1983-11-08 Rai Research Corporation Separator membranes for redox-type electrochemical cells
EP0120139A2 (en) * 1982-12-27 1984-10-03 Toyo Boseki Kabushiki Kaisha Carbon fibre electrode, particularly for a regenerative fuel cell
US4477403A (en) * 1983-05-26 1984-10-16 Teledyne Industries, Inc. Method of making an electrochemical sensor
US4834772A (en) * 1988-02-26 1989-05-30 Cape Cod Research, Inc. Battery electrolyte
US4871428A (en) * 1988-03-24 1989-10-03 C & D Charter Power Systems, Inc. Method for in situ forming lead-acid batteries having absorbent separators
US5194341A (en) * 1991-12-03 1993-03-16 Bell Communications Research, Inc. Silica electrolyte element for secondary lithium battery
US5593796A (en) * 1992-02-10 1997-01-14 C & D Charter Power Systems, Inc. Recombinant lead-acid cell and long life battery
US5882721A (en) * 1997-05-01 1999-03-16 Imra America Inc Process of manufacturing porous separator for electrochemical power supply
US5948464A (en) * 1996-06-19 1999-09-07 Imra America, Inc. Process of manufacturing porous separator for electrochemical power supply
US6148503A (en) * 1999-03-31 2000-11-21 Imra America, Inc. Process of manufacturing porous separator for electrochemical power supply
EP1095419A1 (en) * 1998-06-09 2001-05-02 Farnow Technologies Pty. Ltd. Redox gel battery
US6316142B1 (en) 1999-03-31 2001-11-13 Imra America, Inc. Electrode containing a polymeric binder material, method of formation thereof and electrochemical cell
US20030186107A1 (en) * 2002-03-04 2003-10-02 Maston Valerie A. High performance fuel cells
US20100323264A1 (en) * 2009-04-06 2010-12-23 A123 Systems, Inc. Fuel system using redox flow battery
US20110045332A1 (en) * 2008-07-07 2011-02-24 Enervault Corporation Redox Flow Battery System for Distributed Energy Storage
US20110200848A1 (en) * 2008-06-12 2011-08-18 Massachusetts Institute Of Technology High energy density redox flow device
US20110223450A1 (en) * 2008-07-07 2011-09-15 Enervault Corporation Cascade Redox Flow Battery Systems
US8916281B2 (en) 2011-03-29 2014-12-23 Enervault Corporation Rebalancing electrolytes in redox flow battery systems
US8980484B2 (en) 2011-03-29 2015-03-17 Enervault Corporation Monitoring electrolyte concentrations in redox flow battery systems
US8993159B2 (en) 2012-12-13 2015-03-31 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US9123923B2 (en) 2010-12-10 2015-09-01 Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences Use of porous membrane and composite membrane thereof in redox flow energy storage battery
US9362583B2 (en) 2012-12-13 2016-06-07 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US9484569B2 (en) 2012-06-13 2016-11-01 24M Technologies, Inc. Electrochemical slurry compositions and methods for preparing the same
US9614231B2 (en) 2008-06-12 2017-04-04 24M Technologies, Inc. High energy density redox flow device
US11005087B2 (en) 2016-01-15 2021-05-11 24M Technologies, Inc. Systems and methods for infusion mixing a slurry based electrode
US11909077B2 (en) 2008-06-12 2024-02-20 Massachusetts Institute Of Technology High energy density redox flow device

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56125074A (en) * 1980-03-04 1981-10-01 Samy Kogyo Kk Longitudinal game machine
JPS57169624A (en) * 1981-04-13 1982-10-19 Babcock Hitachi Kk Detecting method for leakage of liquid level indicator
DE102014104601A1 (en) * 2014-04-01 2015-10-01 Schmid Energy Systems Gmbh Electrochemical cell, in particular for a redox flow battery, and method of production

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3392103A (en) * 1963-11-29 1968-07-09 Mc Donnell Douglas Corp Inorganic permselective membranes
US3497394A (en) * 1963-11-29 1970-02-24 Mc Donnell Douglas Corp Inorganic permselective membranes and method of making same
US3497389A (en) * 1964-10-20 1970-02-24 Mc Donnell Douglas Corp Ion exchange membrane and fuel cell containing same

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH93807A (en) * 1919-01-20 1922-04-01 Jennings Thatcher Charles Diaphragm for electric batteries and electrolytic apparatus.
FR634480A (en) * 1926-06-15 1928-02-18 Silica Gel Corp Accumulator battery
BE527979A (en) * 1950-06-13
BE528501A (en) * 1953-04-29
US2923757A (en) * 1957-03-27 1960-02-02 Mallory & Co Inc P R Dry cell
GB838310A (en) * 1957-06-26 1960-06-22 Crompton Parkinson Ltd Improvements relating to armouring and separating sheets for secondary batteries
GB1056273A (en) * 1962-07-09 1967-01-25 Chloride Batteries Ltd Improvements relating to separators for the plates of electric storage batteries
JPS5435655B2 (en) * 1974-08-12 1979-11-05

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3392103A (en) * 1963-11-29 1968-07-09 Mc Donnell Douglas Corp Inorganic permselective membranes
US3497394A (en) * 1963-11-29 1970-02-24 Mc Donnell Douglas Corp Inorganic permselective membranes and method of making same
US3497389A (en) * 1964-10-20 1970-02-24 Mc Donnell Douglas Corp Ion exchange membrane and fuel cell containing same

Cited By (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4370392A (en) * 1981-06-08 1983-01-25 The University Of Akron Chrome-halogen energy storage device and system
US4414090A (en) * 1981-10-01 1983-11-08 Rai Research Corporation Separator membranes for redox-type electrochemical cells
EP0120139A2 (en) * 1982-12-27 1984-10-03 Toyo Boseki Kabushiki Kaisha Carbon fibre electrode, particularly for a regenerative fuel cell
EP0120139A3 (en) * 1982-12-27 1986-08-27 Toyo Boseki Kabushiki Kaisha Carbon fibre electrode, particularly for a regenerative fuel cell
US4477403A (en) * 1983-05-26 1984-10-16 Teledyne Industries, Inc. Method of making an electrochemical sensor
US4834772A (en) * 1988-02-26 1989-05-30 Cape Cod Research, Inc. Battery electrolyte
US4871428A (en) * 1988-03-24 1989-10-03 C & D Charter Power Systems, Inc. Method for in situ forming lead-acid batteries having absorbent separators
US5194341A (en) * 1991-12-03 1993-03-16 Bell Communications Research, Inc. Silica electrolyte element for secondary lithium battery
WO1993011571A1 (en) * 1991-12-03 1993-06-10 Bell Communications Research, Inc. Silica electrolyte element for secondary lithium battery
US5593796A (en) * 1992-02-10 1997-01-14 C & D Charter Power Systems, Inc. Recombinant lead-acid cell and long life battery
US5645957A (en) * 1992-02-10 1997-07-08 C & D Charter Power Systems, Inc. Lead-acid battery having a cover extending beyond a jar
US5695891A (en) * 1992-02-10 1997-12-09 C & D Charter Power Systems, Inc. Battery thermal management system
US5851695A (en) * 1992-02-10 1998-12-22 C & D Technologies, Inc. Recombinant lead-acid cell and long life battery
US6667130B2 (en) 1992-02-10 2003-12-23 C&D Charter Holdings, Inc. Recombinant lead-acid cell and long life battery
US5948464A (en) * 1996-06-19 1999-09-07 Imra America, Inc. Process of manufacturing porous separator for electrochemical power supply
US5882721A (en) * 1997-05-01 1999-03-16 Imra America Inc Process of manufacturing porous separator for electrochemical power supply
EP1095419A4 (en) * 1998-06-09 2005-06-15 Farnow Technologies Pty Ltd Redox gel battery
EP1095419A1 (en) * 1998-06-09 2001-05-02 Farnow Technologies Pty. Ltd. Redox gel battery
US6720107B1 (en) * 1998-06-09 2004-04-13 Farnow Technologies Pty. Ltd. Redox gel battery
US6316142B1 (en) 1999-03-31 2001-11-13 Imra America, Inc. Electrode containing a polymeric binder material, method of formation thereof and electrochemical cell
US6148503A (en) * 1999-03-31 2000-11-21 Imra America, Inc. Process of manufacturing porous separator for electrochemical power supply
US20030186107A1 (en) * 2002-03-04 2003-10-02 Maston Valerie A. High performance fuel cells
US11909077B2 (en) 2008-06-12 2024-02-20 Massachusetts Institute Of Technology High energy density redox flow device
US9614231B2 (en) 2008-06-12 2017-04-04 24M Technologies, Inc. High energy density redox flow device
US11342567B2 (en) 2008-06-12 2022-05-24 Massachusetts Institute Of Technology High energy density redox flow device
US20110200848A1 (en) * 2008-06-12 2011-08-18 Massachusetts Institute Of Technology High energy density redox flow device
US10236518B2 (en) 2008-06-12 2019-03-19 24M Technologies, Inc. High energy density redox flow device
US8722227B2 (en) 2008-06-12 2014-05-13 Massachusetts Institute Of Technology High energy density redox flow device
US9786944B2 (en) 2008-06-12 2017-10-10 Massachusetts Institute Of Technology High energy density redox flow device
US20110045332A1 (en) * 2008-07-07 2011-02-24 Enervault Corporation Redox Flow Battery System for Distributed Energy Storage
US8906529B2 (en) 2008-07-07 2014-12-09 Enervault Corporation Redox flow battery system for distributed energy storage
US20110117411A1 (en) * 2008-07-07 2011-05-19 Enervault Corporation Redox Flow Battery System for Distributed Energy Storage
US20110223450A1 (en) * 2008-07-07 2011-09-15 Enervault Corporation Cascade Redox Flow Battery Systems
US8785023B2 (en) 2008-07-07 2014-07-22 Enervault Corparation Cascade redox flow battery systems
US8778552B2 (en) 2009-04-06 2014-07-15 24M Technologies, Inc. Fuel system using redox flow battery
US20100323264A1 (en) * 2009-04-06 2010-12-23 A123 Systems, Inc. Fuel system using redox flow battery
US9293781B2 (en) 2009-04-06 2016-03-22 24M Technologies, Inc. Fuel system using redox flow battery
US9123923B2 (en) 2010-12-10 2015-09-01 Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences Use of porous membrane and composite membrane thereof in redox flow energy storage battery
US8916281B2 (en) 2011-03-29 2014-12-23 Enervault Corporation Rebalancing electrolytes in redox flow battery systems
US8980484B2 (en) 2011-03-29 2015-03-17 Enervault Corporation Monitoring electrolyte concentrations in redox flow battery systems
US9484569B2 (en) 2012-06-13 2016-11-01 24M Technologies, Inc. Electrochemical slurry compositions and methods for preparing the same
US9184464B2 (en) 2012-12-13 2015-11-10 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US9831519B2 (en) 2012-12-13 2017-11-28 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US9831518B2 (en) 2012-12-13 2017-11-28 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US9385392B2 (en) 2012-12-13 2016-07-05 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US10483582B2 (en) 2012-12-13 2019-11-19 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US11018365B2 (en) 2012-12-13 2021-05-25 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US9362583B2 (en) 2012-12-13 2016-06-07 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US11811119B2 (en) 2012-12-13 2023-11-07 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US8993159B2 (en) 2012-12-13 2015-03-31 24M Technologies, Inc. Semi-solid electrodes having high rate capability
US11005087B2 (en) 2016-01-15 2021-05-11 24M Technologies, Inc. Systems and methods for infusion mixing a slurry based electrode

Also Published As

Publication number Publication date
DE2732481C2 (en) 1985-11-07
DE2732481A1 (en) 1978-01-26
AU508895B2 (en) 1980-04-03
IT1081026B (en) 1985-05-16
AU2713377A (en) 1979-01-25
JPS5313142A (en) 1978-02-06
FR2358920A1 (en) 1978-02-17
GB1580954A (en) 1980-12-10
CA1080303A (en) 1980-06-24
FR2358920B1 (en) 1983-12-23

Similar Documents

Publication Publication Date Title
US4018971A (en) Gels as battery separators for soluble electrode cells
US3288641A (en) Electrical energy storage apparatus
US4133941A (en) Formulated plastic separators for soluble electrode cells
US5545492A (en) Electrochemical apparatus for power delivery utilizing an air electrode
US4370392A (en) Chrome-halogen energy storage device and system
US4309372A (en) Method of making formulated plastic separators for soluble electrode cells
JP3068853B2 (en) Solid state electrochemical battery
Vafiadis et al. Evaluation of membranes for the novel vanadium bromine redox flow cell
US5601938A (en) Carbon aerogel electrodes for direct energy conversion
US3297484A (en) Electrode structure and fuel cell incorporating the same
US3276910A (en) Ion transfer medium for electrochemical reaction apparatus
US3116170A (en) Gaseous fuel cells
US5422197A (en) Electrochemical energy storage and power delivery process utilizing iron-sulfur couple
US4469761A (en) Rechargeable lithium/sulfur ammoniate battery
EP0068508A2 (en) Methanol fuel cell
US20050260460A1 (en) Secondary battery and method of generating electric power
JPH09223513A (en) Liquid circulating type battery
US4687715A (en) Zirconium pyrophosphate matrix layer for electrolyte in a fuel cell
US3447968A (en) Electrical energy storage device and method of storing electrical energy
JPH05505492A (en) Electrochemical cathodes and their materials
EP0463542B1 (en) Gas-recirculating electrode for electrochemical system
Hammond et al. An electrochemical heat engine for direct solar energy conversion
JPH0534784B2 (en)
US3719528A (en) Fuel cell containing an electrolyte consisting of an aqueous solution of arsenic acid
US3403054A (en) Fuel cell with ion-permeable membrane